2-Aryl-3-arylaminoisoxazol-5(2H)-ones as sources of indoles and imidazo[1,2-a]pyridines

2-Aryl-3-arylaminoisoxazol-5(2H)-ones undergo solvolysis to form 1,3-dipoles that undergo intramolecular cyclisation to form either imidazopyridines or indoles. The mode of cyclisation is controlled by the electronegativity of the aryl substituents.